Food, Inc. (R) ***

It's hard to stomach, but go see it.

Remember how, after seeing Super Size Me, you couldn't stomach the thought of eating at McDonald's ever again? (Ground chicken beaks in my Chicken McNuggets? Shudder!) Get ready to lose your appetite all over again -- only not just for fast food this time.

In director Robert Kenner's illuminating and occasionally revolting documentary Food, Inc., we get a wide-ranging look at food production and how giant corporations essentially have taken over the industry, with serious consequences to the consumer.

Using research by authors Eric Schlosser (Fast Food Nation) and Michael Pollan (The Omnivore's Dilemma) as a starting point (both are interviewed in the film), Food, Inc. serves as a primer on the state of agriculture and meat farming in the United States. The film's brief running time doesn't allow director Kenner to delve into too much detail, but he covers enough ground to raise highly troubling questions about the methods and practices used in keeping your supermarket shelves stocked with fresh meat, potato chips and soft drinks.

If Food, Inc. were Star Wars, its Darth Vader would be corn, that seemingly innocuous vegetable present in one form or another in everything from Coca-Cola to Sweet'N Low to Duracell batteries. Corn is also what cattle have been taught to eat instead of grass, because it fattens them up quicker, allowing breeders a faster turnaround on their crops and drives the price of beef down.

Except cattle, by nature, were never meant to eat corn, which explains the sudden rise in E. coli outbreaks and massive meat recalls over the last decade. In one of the film's most heartbreaking moments, we meet Barbara Kowalcyk, whose son Kevin died in 2002 after eating an E. coli-infected hamburger. Kowalcyk has been trying, to no avail, to get Congress to pass ''Kevin's Law,'' which would give the government the right to shut down plants producing contaminated meats.

Food, Inc. argues that part of the reason why the food industry is so difficult to regulate is that many of the government officials currently assigned to watchdog roles were once employed by the companies they now keep tabs on. The number of food safety inspections by the FDA has plummeted to less than a fifth of what it was 30 years ago.

But while the cost of food keeps dropping in this country, medical costs keep rising. Food, Inc. draws a correlation between working-class parents who feed their kids from a burger joint's one-dollar menu instead of buying more expensive fruits and vegetables and the ballooning rates of obesity, diabetes and other ailments afflicting the U.S. population.

There is hope on the horizon -- Walmart representatives who are seen in the film ordering organic dairy products from Stonyfield Farms, claim sales and demand for the products are growing -- but Food, Inc. proves we've still got a long way to go. Next time you're about to bite into that delicious (and cheap) double cheeseburger, try not to think too hard about the fact that the meat was treated with ammonia to kill that pesky E. coli -- and that the patty is composed of meat from several hundred cows.